Devices which allow the user to manually enter coordinate data into a host computer make use of various systems including electromagnetic induction system, electrostatic capacitance system, transparent electrode system, and optical detection system. Among these devices, the device of the optical detection type has attracted interest from viewpoint of reliability and ease with which the device is operated. Specifically, this optical detection type device is mounted on the face of a display device. The user can specify coordinates in a noncontacting manner simply by depressing a desired location on the display device with a finger or other means.
A conventional coordinate data entry device of the optical detection type is shown in FIGS. 8-11. The entry device, shown to be installed on the face of a display device 3 in FIG. 8, is shaped into a substantially rectangular form. This entry device is primarily composed of a frame 1 having an opening 2 at its center, arrays of light-emitting devices 4 such as light-emitting diodes, arrays of light-receiving devices 5 such as phototransistors, and an arithmetic section 6. The display device 3 consists, for example, of a cathode-ray tube and has a viewing screen 3a. The arrays 4 and 5 are disposed around the screen 3a, i.e., on the back side of the frame 1, in such a way that one array of light-emitting devices 4 is opposite to one array of light-receiving devices 5 and that the other array of light-emitting devices 4 is opposite to the other array of light-receiving devices 5. Each light-emitting device 4 emits light toward the corresponding light-receiving device 5 along a light path 12. When any one of such light paths 12 is blocked, the arithmetic section 6 detects it and enters the coordinate data into a host computer (not shown).
An operation panel 2a comprising a video display terminal filter is mounted in the opening 2. This panel is installed on the viewing screen 3a of the display device 3 to prevent the screen from becoming fouled or dust from adhering to it. Further, it prevents fatigue of the user's eye. Each light-emitting device 4 has a light-emitting section 4a. Each light-receiving device 5 has a light-receiving section 5a. The light-emitting devices 4 and the light-receiving devices 5 are rigidly secured to a baseplate 7 mounted on the frame 1, in such a manner that the light-receiving sections 5a face their respective light-emitting sections 4a. The arrays 4 and 5 are arranged along the sides of the baseplate 7 to detect only a certain operation region A, corresponding to the display region that is presented on the viewing screen 3a for data entry. The arrays 4 and 5 do not extend to marginal regions B to prevent their optical axes from intersecting each other. A light-blocking plate 8 is disposed in front of the light-receiving section 5a of each light-receiving device 5, and is provided with a hole 8a to permit the light coming from the corresponding light-emitting device 4 to pass through it. The hole 8a has a certain area and a certain depth. In order to cut off visible light, an infrared filter 9 is mounted in front of the light-blocking plate 8. A similar infrared filter 9 is mounted over the whole periphery of the front opening of the light-emitting device 4. Accordingly, invisible light paths 12 are formed by the use of the infrared filter 9 on the side of the operation panel 2a that does not face the viewing screen 3a.
When coordinates are detected, the position on the screen 3a whose coordinates are to be entered is depressed with a finger 10 or other means from above the operation panel 2a, as shown in FIGS. 8-10. The light paths 12 are formed along the surface of the panel 2a. The light-emitting devices 4 are successively caused to emit for making scan along the x- and y-axes. The emitted light beams are successively detected by the light-receiving devices 5. Thus, any blocked light path 12 can be detected, and is specified by the arithmetic section 6 which then sends the coordinate data to the host computer (not shown).
Another general structure for mounting the light-emitting devices 4 and the light-receiving devices 5 and for use in the conventional optical coordinate data entry device is shown in FIG. 11, where a printed-wiring board 7 forms a base. An optical semiconductor device 32 that is a light-emitting or -receiving device is fabricated separately. This device 32 is mounted on the board 7 and soldered at 33. Then, light-blocking plates 34 and a stop member 35 for gathering light are mounted. Each array is manufactured in this way, and the arrays are electrically interconnected.
The conventional array for an optical coordinate data entry device is constructed as described just above. Hence, the array is made up of a large number of components and require many steps to manufacture, increasing the product price greatly. Further, the accuracy may differ among optical devices.